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18. Investigating Osmosis > Procedure IV-2-1: Observing Osmosis in Chicken Eggs
Eggshells are primarily calcium carbonate, a chemical compound that is also familiar in the form of chalk, limestone, and marble. Calcium carbonate reacts readily with acids to form calcium salts and carbon dioxide gas. In this procedure, we’ll immerse two raw eggs in an acidic solution and allow the reaction to consume the eggshells, leaving only the raw eggs within the membrane that surrounds the white and yolk.
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Place two raw eggs in a large foam cup or other suitable container.
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Fill the cup with distilled white vinegar, ensuring that both eggs are fully submerged, and cover the cup loosely to allow carbon dioxide gas to escape. (It’s okay for the eggs to be in contact.) Keeping the cup in the refrigerator may slow down the reaction somewhat, but it also keeps the eggs from spoiling. That won’t matter unless you accidentally break the egg membrane, in which case it’s better if the eggs aren’t spoiled.